Your results are euthyroid. I can't see why you would be experiencing pain with those results but if the pain is worse since reducing Carbimazole dose to 5mg it is possible you may have become hyperthyroid. I would ask your GP to retest your thyroid levels now that you've been on the reduced dose for 2 months.

Ask your GP to test vitamin D, ferritin, B12 and folate which are commonly low/deficient in thyroid patients. When supplementing D3 vitD should be checked annually at least to ensure you are not over supplementing to toxic levels.

I am not a medical professional and this information is not intended to be a substitute for medical advice from your own doctor. Please check with your personal physician before applying any of these suggestions.